The present invention relates to a geometrical instrument and method for traversing and surveying a surface. Specifically, a method and vehicle are disclosed for providing data from which three-dimensional coordinates of a large number of points along the path of the vehicle on a surface may be calculated. The data provided by such a vehicle and method may be used in large-scale land surveys, for example, as a part of flood control analysis or as an aid in highway design. The method may also be used to profile existing roads or to provide reference points for use in conjunction with the preparation of topographical and/or planimetric maps from aerial photographs.
Known wheeled devices for road or railroad vehicles have been provided for measuring parameters of the surface over which the vehicles travel. Such devices are illustrated for example in U.S. Pat. No. 3,594,912 to Sauterel, U.S. Pat. No. 3,263,332 to Plasser, and Belgian Pat. No. 562,683 to Maysounave. These devices are, however, designed to measure the surface contour over which the vehicle passes with respect to immediately adjacent road or track areas and do not provide data from which locational coordinates or points on the vehicle path can be determined.
Accordingly, it is an object of the present invention to provide a survey vehicle for providing data from which locational coordinates of points on the vehicle path can be determined.
It is another object of the present invention to provide a method for surveying a surface to determine three-dimensional coordinates of points along a path on the surface.
Known surveying devices, adapted to be carried by a land vehicle, employ gyro systems or compasses to provide reference data from which locational coordinates of the vehicle may be calculated. Such systems are illustrated, for example in U.S. Pat. No. 3,604,119 to Inoue, and U.S. Pat. No. 3,002,282 to Rumrill. A commercial system employing an inertial platform coupled with gyroscopes and accelerometers has been built by Litton Guidance and Control Systems. See "Results of Tests Using An Inertial Rapid Geodetic Survey System (RGSS)", Proceedings of the American Congress on Surveying and Mapping, 37th Annual Meeting, p. 100, Library of Congress Catalog No. 50-33534. Such systems use the gyroscope to provide fixed reference data. The position of the vehicle is determined by measuring movement of the vehicle with respect to the reference data.
Such systems have a disadvantage in that they are difficult and expensive to fabricate due, principally, to the complexity and close tolerances required to construct an operable inertial platform for terrain surveys similar to that employed in missile guidance systems. In operation, the gyroscopic systems have several disadvantages. First, start up of the system necessitates the time consuming process of initializing the gyroscopes. Secondly, the vehicle must be stopped at intervals throughout the survey to permit the system to compensate for precession of the gyroscopes. Finally, rapid acceleration and deceleration of the vehicle, such as that produced when the vehicle is driven over chuck holes, tend to destabilize the gyroscopes with consequent degradation of the survey measurements.
Accordingly, it is an object of the present invention to provide an automatic high-speed surveying device which is inexpensive to fabricate.
It is another object of the present invention to provide a survey vehicle and method which does not employ one or more gyroscopes to provide a reference for determination of locational coordinates of the vehicle.
It is another object of the present invention to provide a survey vehicle device which may be continuously moved over a surface to make measurements from which three-dimensional coordinates of points on the path of travel may be determined.
It is another object of the present invention to provide a survey vehicle which may be moved over a surface to produce data from which three-dimensional coordinates of points on the path of the vehicle may be calculated, which vehicle produces accurate data which is unaffected by rapid acceleration or deceleration of the vehicle during travel along the path.
Other known vehicle mounted survey devices employ one or more pendulums as sources of a reference axis. Such devices are illustrated for example in U.S. Pat. No. 2,647,323 to Johnson et al, and U.S. Pat. No. 2,552,890 to Eisler. Such systems have the disadvantages, inter alia, that (1) they measure only the elevation of the vehicle; and (2) the quality of their measurements is degraded by acceleration and deceleration of the vehicle which disturbs the equilibrium of the pendulum.
Accordingly, it is another object of the present invention to provide a survey vehicle and method which does not employ a pendulum or other gravity sensitive means to provide a reference direction for determination of locational coordinates of the vehicle.
These and other objects and features will become apparent from the following description when read with the claims and the appended drawings.